Why is Marley Creek so clean?

Brandi Bottalico, bbottalico@capgaznews.com

The sign that prohibited swimming in Marley Creek for decades was removed last summer and bacteria levels are among the lowest in the county after last week's heavy storm, but the reasons for the improvement remain a mystery.

South River Federation Riverkeeper Diana Muller sampled the historically dirty creek in Glen Burnie Wednesday, a week after a record rainfall, and found impressive results — a bacteria reading of 34. Maryland's state law defines anything below a 104 colony count of the enterococci bacteria to be healthy, Muller said.

"That bacteria concentration, it's basically from poop," she said. "I would say Marley Creek is relatively healthier than the South River."

After a heavy rain, stormwater runoff from the land brings high concentrations of bacteria, making waters unsafe for swimming for a short period.

"The fact that it dropped a week later is a really good sign," Muller said. "We have a low flushing rate in the tidal areas and tributary."

Tom Zolper listed 2000 as one of the highest bacteria levels from a study done on Marley Creek between 2005 and 2007 by the Maryland Department of the Environment.

Zolper, spokesman for the Chesapeake Bay Foundation, said although the recent bacteria reading was low, it doesn't indicate that the bacteria levels in the creek have improved.

"The bacteria levels go down even in a place like Marley Creek," he said. "When it rains, the levels go up, and when it dries, the levels go down."

There is no way to tell whether the levels have been consistently low because the Anne Arundel County Health Department no longer tests Marley Creek.

Councilman John Grasso lives on the creek and started an initiative to install aerating fountains in the waterway in 2010. Thirty-two of the fountains are installed on Marley and Furnace creeks to pump oxygen into the water to prevent fish kills like the one that happened in 2012 after a major sewage spill on the Patapsco River.

Grasso said he has no doubt his fountains have contributed to the low bacteria levels and overall improvement of the creek.

"We had a headache with the creek and I came up with the aspirin," he said. "These fountains are kicking butt."

Muller said the aerating fountains could contribute to higher dissolved oxygen levels, improving conditions for fish, crabs and other life in the water. Grasses and mussels are now growing in the creek that previously did not grow there, she said. But she said they won't effect bacteria levels.

"Any time you can oxygenate a water column is good," she said. "It's not the cure ... but it's a pill to kind of remediate the problem temporarily."

Muller hopes to do consistent testing of the creek next year and wants to work with Grasso to do more in-depth research.

She expressed frustration that the county and state no longer monitor the creek, even after a rainstorm, but instead issuing a blanket warning of high bacteria levels.

The county has a 48-hour no swimming/contact warning after any rainfall of a half inch or more, said Elin Jones, health department spokeswoman. The Health Department monitors beach areas on South, West, Rhodes, Patapsco, Severn, and Magothy rivers, Weems, Stoney and Bodkin creeks, as well as the Chesapeake Bay.

They discontinued sampling on Furnace, Marley and Rock creeks in 2013, saying there were no beach areas on the waterways.